Heated, vacuum-pressure press

ABSTRACT

A combination heated, vacuum and pressure press is provided for facilitating the transfer of a substance from a workpiece to which it is weakly adhered to a substrate to which it is more permanently adhered by means of a heat-activated thermosetting adhesive. The press consists of a platen having vacuum passages therein with a flexible blanket overlying the platen so that it may be drawn tightly to the platen upon application of the vacuum and a cover in the form of a dome sealingly engaging the platen and forming a chamber thereover, the cover having an internal heating element and the press having means to pressurize the interior of the chamber formed between the platen and the cover so that positive pressure can be exerted on the flexible blanket while the interior of the dome is at the same time heated to assure perfect transfer of a substance from a workpiece to a substrate underneath the blanket.

United States Patent [19] Bond 1 [4 June 25, 1974 HEATED, VACUUM-PRESSURE PRESS [75] Inventor: Herbert M. Bond, Stillwater, Wash.

[73] Assignee: Buckbee-Mears Company, St. Paul,

Minn.

[22] Filed: June 6, 1972 [21] Appl. No.: 260,338

Related US. Application Data [62] Division of Ser. No. 869,594, Oct. 27, 1969,

[5 6] References Cited UNITED STATES PATENTS 1,906,821 5/1933 Sherts 100/90 1,956,168 4/1934 Fix et al. 100/93 P 2,975,476 3/1961 Burke 100/211 X Levetan 156/285 X Primary ExaminerPeter Feldman Attorney, Agent, or FirmJacobson and Johnson [57] ABSTRACT A combination heated, vacuum and pressure press is provided for facilitating the transfer of a substance from a workpiece to which it is weakly adhered to a substrate to which it is more permanently adhered by means of a heat-activated thermosetting adhesive. The press consists of a platen having vacuum passages therein with a flexible blanket overlying the platen so that it may be drawn tightly to the platen upon application of the vacuum and a cover in the form of a dome sealingly engaging the platen and forming a chamber thereover, the cover having an internal heating element and the press having means to pressurize the interior of the chamber formed between the platen and the cover so that positive pressure can be exerted on the flexible blanket while the interior of the dome is at the same time heated to assure perfect transfer of a substance from a workpiece to a substrate underneath the blanket.

1 Claim, 5 Drawing Figures 1 HEATED, VACUUM-PRESSURE PRESS This is a division of application Ser. No. 869,594, filed Oct. 27, 1969', now abandoned.

This invention relates to a vacuum press and more particularly relates to a heated, vacuum-pressure press for facilitating the transfer of a substance from one substrate to another in a rapid and efficient manner on the press.

There are many instances in industry where it is desired to form a substance, in the form of an article such as a decal, a printed circuit, a metallized coating, etc. on one substrate and then transfer it from that substrate to a more permanent backing or substrate by the use of a thermosetting adhesive to adhere the substance to the second substrate. Heretofore there has been no simple straightforward way for doing this and a series of operations have been required to press the two substrates together to cause good contact between the substance to be transferred and the substrate to which it is to be transferred combined with subsequent heating operations at a later stage of the process and culminating in yet another stage for the separation of the substrates from one another with the substance transferred to the proper substrate.

This invention provides a greatly simplified procedure capable of being carried out on a single piece of apparatus to accomplish the entire transfer in a very short period of time and which procedure requires a minimum of skill in its operation.

In accordance with this invention a combination heated, vacuum and pressure press is provided comprising a platen having vacuum passages opening into the face thereof, a dome overlying the platen and sealed to the platen around the platen area covered by the vacuum openings, means maintaining the dome and the platen in sealing contact with one another upon pressurization of the dome, a non-porous, heatconductive, flexible blanket interposed between the dome and the platen within the area sealed by the dome edge, means for pressurizing the interior of the dome with gas to exert positive, super atomospheric; pressure onthe blanket after the blanket is held in placeby a vacuum, and means within the dome to heat the interior thereof.

Using the novel apparatus just described, a simple and efficient method for transferring substances from one substrate to another is provided. The apparatus is particularlyuseful in the transfer of the delicate printed circuits from a workpiece to a transfer substrate which is in the form of a thin, self-sustaining, flexible film or sheet of heat-resistant electrical grade polymer.

In the practice of the process the workpiece is placed on the platen, a flexible film having a thermosetting adhesive coating thereon is placed thereover with the thermosetting adhesive coated face in contact with the surface of the workpiece. The blanket is then laid over this assembly with the blanket edges extending beyond the assembly. A vacuum is then drawn to draw the workpiece tight againstthe platen and to draw the flexible, preferably elastic, blanket taut over the assembly. There'upon, or therebefore, the dome is pressed in place to form a sealed hollow chamber overlying the platen and the blanketed assembly thereon. The interior of the dome is thenpressurized and heated to assure good even contact of the flexible film to the metal circuit on the workpiece and to activate the adhesive to adhesively secure the circuit permanently to the flexible film. Upon release of the pressure from the dome and of the vacuum from the platen (not necessarily in the order stated), the dome is raised, the blanket removed and the flexible film with the circuit attached separated from the workpiece.

The inventionwill be described in more detail in conjunction with the accompanying drawings wherein:

FIG. 1 is a side elevational view of a combination heat, vacuum-pressure press made in accordance with this invention;

FIG. 2 is a top view of the vacuum platen of the press;

FIG. 3 is a bottom view of the dome of the press;

FIG. .4 is a cross-sectional view taken substantially along the plane of section line 4-4 of FIG. I illustrating the interior of the press during operation; and

FIG. 5 is a side elevational view of the transfer of a substance from one substrate to another using the apparatus illustrated in F IGS. 1-4.

Referring first to FIG. 1, the combination heated, vacuum-pressure press of this invention is designated in its entirety by the numeral 10. It is shown to comprise a supporting frame 12 supporting a horizontal rectangular frame 14, which table carries a platen l6. Vertical corner members 18 rising from the horizontal frame 14 having slidably mounted thereon a second horizontal rectangular frame 20 for movement toward and away from the platen l6. Beneaththe horizontal frame 20 and carried thereby. is a dome22, the peripheral edge of which is adapted to seal to the platen 16 when the dome is pressed into place against the platen.

Projecting centrally upwardly from the dome and fixedly attached thereto is a piston 24 carried within a hydraulic or pneumatic lift cylinder 26. The lift cylinder is mounted on a top horizontal frame 28 fixedly carried by the top of the corner supports 18. The function of the lift cylinder is to raise and lower the dome 22 and to maintain the dome in place in sealing relation around its periphery to the platen 16. There is also illustrated a safety lock pin 30 engaging the frame 20 carrying the dome and the frame 14 carrying the platen to prevent inadvertent droppingof the dome. The operation of this safety lock pin is controlled by a safety lock cylinder 32.

Illustrated somewhat schematically is a high pressure tube 34 leading from a high pressure air supply (not shown) through the valve 36 into the passage 38 opening into the face of the platen 16; this is particularly illustrated by the small cross-sectional detail showing in FIG. 1 for this purpose. There is also provided a vacuum line 40 leading from a vacuum pump 42 through a vacuum shut-off valve 44 into vacuum passages 46, shown in the small cross-sectional detail in FIG. 1 for this purpose, also opening into the face of platen 16.

In FIG. 2 the top surface of the platen 16 is illustrated showing the vacuum openings 46 therein and also illustrating circular sealing groove 48 around the periphery of the portion of the platen 16 having the vacuum openings therethrough. Also shown is the opening 38 for admitting gas under pressure to the interior of the dome through the platen 16. As will be noted this opening 38 is inside the circular area of the platen l6 surrounded by the sealing groove 48 but outside of the circular periphery of the vacuum passage area of the platen.

In FIG. 3 the interior of the dome 22 is illustrated. The dome has a concave interior with a large heating element 50 therein. The bottom periphery of the dome is flat and carries therewithin a sealing ring 52 which, when the dome is pressed in place against the platen 16, sits within the groove 48 to form a sealed chamber 54 (FIG. 4) above the portion of the platen 16 surrounded by the sealing groove 48.

In FIG. 4 the operation of the device is most clearly illustrated. In that figure the dome 22 is shown pressed in place against the platen 16 with the sealing ring 52 sealing the-periphery of the dome to the platen. A black rubber blanket 56 is shown stretched over the work assembly, designated in its entirety by the numeral 58, and held tightly in place thereby by a vacuum drawn through the vacuum openings 46 in the platen 16. The black rubber blanket 56 is further held tight against the work assembly 58 by pressurizing the chamber 54 through the high pressure line 34 and the interior may at the same time be heated by means of the heating element 50, which may be in the form of a conventional electric heating coil.

The work assembly 58 in the preferred embodiment illustrated is composed of a rigid plate 60 on which a copper or other metal circuit 62 has been deposited by electroforming, or formed thereon by other means, and which is only lightly adherent thereto. Overlying the plate 60, which forms the workpiece, and the circuit 62 is a thin, flexible, self-sustaining film or sheet 64 of electrical grade synthetic polymer, which has the face thereof engaging the metal deposit 62 coated with a normally non-tacky thermosetting adhesive coating (not shown) which, upon thermosetting, also sets to a non-tacky state. By the combination of the vacuum on the rubber blanket 56 and the positive pressure exerted by the compressed gas in the interior of the dome heated by means of the heating coil 50, the metal deposit is rapidly adheredto the thin, flexible backing film 64 to such a degree that it readily and completely separates from the workpiece 60, whereupon it can be removed therefrom as illustrated in FIG. 5.

While the invention has been explained with respect to the transfer of a metal circuit from a plate to a thin film, the apparatus and the method can obviously be used to effect the transfer of a wide variety of materials in a simple and efficient manner.

What is claimed is:

l. A combination heated, vacuum-pressure press for facilitating the adhesion of a substance to a substrate by the utilization of heat and pressure comprising:

a platen surface having a face for receiving a work piece to be assembled under heat and pressure,

said platen surface having a plurality of vacuum passages passing through said platen and adaptable to be connected to a vacuum source;

vacuum source, said vacuum source connected to said plurality of vacuum passages to thereby produce a lower pressure region adjacent the surface of said platen;

a dome disposed above said platen and having a concave bottom for forming a chamber over the face of said platen, said dome having a periphery being adapted for forming sealing engagement around the area of said vacuum passages located on the surface of said platen, said periphery of said dome including a sealing ring for forming sealing engagement between said dome and said platen;

flexible, nonporous heat conductive blanket located between said dome and said platen, said flexible nonporous heat conductive blanket adaptable for covering a work piece which is located on the face of said platen and which is to be assembled by pressure and heat, said flexible nonporous heat conductive blanket operable for applying a force to the opposite sides of the article to be assembled by heat and pressure, said flexible, nonporous heat conductive blanket separating the chamber formed between said platen and said dome into a high pressure region and a vacuum region, said flexible, nonporous heat conductive blanket operable for extending beyond the edges of the work piece to be assembled by pressure and heat and the plurality of vacuum passages located in said platen so that said flexible, nonporous heat conductive blanket is operable for transmitting a force to the article which is to be assembled by pressure and heat, a high pressure gas line opening into the high pressure region in the chamber between said dome and said platen for pressurizing the high pressure region therein with a high pressure gas to thereby produce an internal force;

means for holding said dome against said platen in a heating element located in the high pressure region defined by said platen and said dome, said heating element operable for supplying heat to the article which is to be assembled by heat and pressure. 

1. A combination heated, vacuum-pressure press for facilitating the adhesion of a substance to a substrate by the utilization of heat and pressure comprising: a platen surface having a face for receiving a work piece to be assembled under heat and pressure, said platen surface having a plurality of vacuum passages passing through said platen and adaptable to be connected to a vacuum source; a vacuum source, said vacuum source connected to said plurality of vacuum passages to thereby produce a lower pressure region adjacent the surface of said platen; a dome disposed above said platen and having a concave bottom for forming a chamber over the face of said platen, said dome having a periphery being adapted for forming sealing engagement around the area of said vacuum passages located on the surface of said platen, said periphery of said dome including a sealing ring for forming sealing engagement between said dome and said platen; a flexible, nonporous heat conductive blanket located between said dome and said platen, said flexible nonporous heat conductive blanket adaptable for covering a work piece which is located on the face of said platen and which is to be assembled by pressure and heat, said flexible nonporous heat conductive blanket operable for applying a force to the opposite Sides of the article to be assembled by heat and pressure, said flexible, nonporous heat conductive blanket separating the chamber formed between said platen and said dome into a high pressure region and a vacuum region, said flexible, nonporous heat conductive blanket operable for extending beyond the edges of the work piece to be assembled by pressure and heat and the plurality of vacuum passages located in said platen so that said flexible, nonporous heat conductive blanket is operable for transmitting a force to the article which is to be assembled by pressure and heat, a high pressure gas line opening into the high pressure region in the chamber between said dome and said platen for pressurizing the high pressure region therein with a high pressure gas to thereby produce an internal force; means for holding said dome against said platen in sealing engagement, said means producing sufficient force to counteract the internal force within said dome and said platen which are produced by pressurizing the high pressure region in the chamber between said dome and said platen with high pressure gas; and a heating element located in the high pressure region defined by said platen and said dome, said heating element operable for supplying heat to the article which is to be assembled by heat and pressure. 